The tunable coordination architectures of a flexible multicarboxylate N-(4-carboxyphenyl)iminodiacetic acid via different metal ions, pH values and auxiliary ligand

{[Pb₃(CPIDA)₂(H₂O)₃]·H₂O}_n1, {[Cd₃(CPIDA)₂(H₂O)₄]·5H₂O}_n2, [Cd(HCPIDA)(bpy)(H₂O)]_n3 (bpy=4,4′-bipyridine) and {[Co₃(CPIDA)₂(bpy)₃(H₂O)₄]·2H₂O}_n4 were synthesized with N-(4-carboxyphenyl) iminodiacetic acid (H₃CPIDA). In 1, the CPIDA³⁻ ligands adopt chelating and bridging modes with Pb(II) to possess a 3D porous framework. In 2D-layer 2, the CPIDA³⁻ ligands display a simple bridging mode with Cd(II). The 2D layers have parallelogram-shaped channels along a axis. With bpy ligands, the HCPIDA²⁻ ligands in 3 show more abundant modes, but 3 still displays a 2D sheet on bc plane for the unidentate bpy molecules. However, in 3D-framework 4, the bpy ligands adopt bridging bidentate at a higher pH value and the CPIDA³⁻ ligands show bis-bidentate modes with Co(II). Additionally, 2D correlation analysis of FTIR was introduced to ascertain the characteristic adsorptions location of the carboxylate groups with different coordination modes in 4 with thermal and magnetic perturbation. Compounds 1, 2 and 4 exhibit the fluorescent emissions at room temperature.     

Taguchi OA16 orthogonal array design for the optimization of cloud point extraction for selenium determination in environmental and biological samples by tungsten-modified tube electrothermal atomic absorption spectrometry

Orthogonal array design (OAD) was applied for the first time to optimize cloud point extraction (CPE) conditions for Se(IV) determination by electrothermal atomic absorption spectrometry (ETAAS) in environmental and biological samples. Selenium was reacted with o-phenylenediamine to form piazselenol in an acidic medium (pH 2). Using Triton X-114, as surfactant, piazselenol was quantitatively extracted into small volume (about 30 μL) of the surfactant-rich phase after centrifugation. Five relevant factors, i.e. surfactant concentration, pH, ionic strength, equilibrium time and temperature were selected and the effects of each factor were studied at four levels on the extraction efficiency of Se(IV) and optimized. The statistical analysis revealed that the most important factors contributing to the extraction efficiency are ionic strength, pH and percent of surfactant. Based on the results obtained from the analysis of variance (ANOVA), the optimum conditions for extraction were established as: pH 6; vial temperature = 50 °C; extraction time = 7 min and 0.3% (w/v) of Triton X-114. The method was permitted to obtain a detection limit of 0.09 ng mL⁻¹ and two linear calibration ranges from 0.6 to 1.0 and 1.0 to 80.0 ng mL⁻¹ Se. The precision (%RSD) of the extraction and determination for the six replicates of Se at 20 ng mL⁻¹ was better than 3.6% and the enrichment factor of 63.5 was achieved. The studied analyte was successfully extracted and determined with high efficiency using cloud point extraction method in water and biological matrices.     

气相色谱-质谱监测1-溴-2,4-二氟苯的合成条件、贡献及纯度

采用气相色谱-质谱（GC—MS）法对1,3-二氟苯溴化产物定性分析,采用了峰面积归一化法对产物进行定量分析,并通过正交设计结合多指标综合评价法优化合成条件。结果表明,通过GC—MS监测,对正交实验Z值结果分析得到最佳制备工艺：四氯化碳为溶剂,反应摩尔比（间二氟苯与液态溴）2：1,5℃下反应12h。产物纯度高于99．50％     

Real‐Time Nanomicroscopy via Three‐Dimensional Single‐Particle Tracking

We developed a new method for real‐time, three‐dimensional tracking of fluorescent particles. The instrument is based on a laser‐scanning confocal microscope where the focus of the laser beam is scanned or orbited around the particle. Two confocal pinholes are used to simultaneously monitor regions immediately above and below the particle and a feedback loop is used to keep the orbit centered on the particle. For moderate count rates, this system can track particles with 15 nm spatial resolution in the lateral dimensions and 50 nm in the axial dimension at a temporal resolution of 32 ms. To investigate the interaction of the tracked particles with cellular components, we have combined our orbital tracking microscope with a dual‐color, wide‐field setup. Dual‐color fluorescence wide‐field images are recorded simultaneously in the same image plane as the particle being tracked. The functionality of the system was demonstrated by tracking fluorescent‐labeled artificial viruses in tubulin‐eGFP expressing HUH7 cells. The resulting trajectories can be used to investigate the microtubule network with super resolution.     

Hydrogen Bonding in Fluorinated Amides: FTIR,Two Dimensional Correlation Spectroscopy and DFT Calculations

Fluorinated macromers with amidic functional groups are used as additives in several high tech applications. We show here how aggregation phenomena related to hydrogen bonding are one of the key factor determining their chemical/physical and macroscopic properties. IR spectra are analyzed depending on different external parameters such as the concentration of amide groups and temperature. The experimental findings have been interpreted by means of DFT (Density Functional Theory) calculations on suitable molecular models. Moreover, 2D correlation spectroscopy has been applied to different sets of data, considering concentration and temperature as perturbing variables. The two dimensional correlation approaches confirmed the computational results and give an overall interpretation of the effects due to concentration and temperature.     

First Colonization of a Spectral Outpost in Random Matrix Theory

We describe the distribution of the first finite number of eigenvalues in a newly-forming band of the spectrum of the random Hermitian matrix model. The method is rigorously based on the Riemann–Hilbert analysis of the corresponding orthogonal polynomials. We provide an analysis with an error term of order N ^−2γ where 1/γ=2ν+2 is the exponent of non-regularity of the effective potential, thus improving even in the usual case the analysis of the pertinent literature. The behavior of the first finite number of zeroes (eigenvalues) appearing in the new band is analyzed and connected with the location of the zeroes of certain Freud polynomials. In general, all these newborn zeroes approach the point of nonregularity at the rate N ^−γ , whereas one (a stray zero) lags behind at a slower rate of approach. The kernels for the correlator functions in the scaling coordinate near the emerging band are provided together with the subleading term. In particular, the transition between K and K+1 eigenvalues is analyzed in detail.      

Wall Rational Functions and Khrushchev’s Formula for Orthogonal Rational Functions

The Nevalinna–Pick algorithm yields a continued fraction expansion of every Schur function, whose approximants are identified. These approximants are quotients of rational functions which can be understood as the rational analogs of the Wall polynomials. The properties of these Wall rational functions and the corresponding approximants permit us to obtain a Khrushchev’s formula for orthogonal rational functions. An introduction to the convergence of the Wall approximants in the indeterminate case is presented. This work was partially realized during two stays of the second author at the Norwegian University of Science and Technology (NTNU) financed respectively by Secretaría de Estado de Universidades e Investigación from the Ministry of Education and Science of Spain and by the Department of Mathematical Sciences of NTNU. The work of the second author was also partially supported by the Spanish grants from the Ministry of Education and Science, project code MTM2005-08648-C02-01, and the Ministry of Science and Innovation, project code MTM2008-06689-C02-01, and by Project E-64 of Diputación General de Aragón (Spain).     

Discrete Entropies of Orthogonal Polynomials

Given a nontrivial Borel measure on ℝ, let p _n be the corresponding orthonormal polynomial of degree n whose zeros are λ _j ⁽ⁿ⁾, j=1,…,n. Then for each j=1,…,n,

The asymptotic behaviour of recurrence coefficients for orthogonal polynomials with varying exponential weights

We consider orthogonal polynomials on the real line with respect to a weight and in particular the asymptotic behaviour of the coefficients a_n,N and b_n,N in the three-term recurrence xπ_n,N(x)=π_n+1,N(x)+b_n,Nπ_n,N(x)+a_n,Nπ_n−1,N(x). For one-cut regular V we show, using the Deift-Zhou method of steepest descent for Riemann-Hilbert problems, that the diagonal recurrence coefficients a_n,n and b_n,n have asymptotic expansions as n→∞ in powers of 1/n² and powers of 1/n, respectively.     

Inverse eigenproblem for -symmetric matrices and their approximation

Let be a nontrivial involution, i.e., R=R⁻¹≠±I_n. We say that is R-symmetric if RGR=G. The set of all -symmetric matrices is denoted by . In this paper, we first give the solvability condition for the following inverse eigenproblem (IEP): given a set of vectors in and a set of complex numbers , find a matrix such that and are, respectively, the eigenvalues and eigenvectors of A. We then consider the following approximation problem: Given an n×n matrix , find such that , where is the solution set of IEP and is the Frobenius norm. We provide an explicit formula for the best approximation solution by means of the canonical correlation decomposition.